Question

The rain-soaked shoes of a person may explode if ground current
from nearby lightning vaporizes the water. The sudden conversion of
water to water vapor causes a dramatic expansion that can rip apart
shoes. Water has density 1000 kg/m3 and requires 2256 kJ/kg to be
vaporized. If horizontal current lasts 2.00 ms and encounters water
with resistivity 120 ·m, length 12.0 cm, and vertical
cross-sectional area 1.3 10-4 m2, what average current is required
to vaporize the water?

Hint:
How much water mass is to be vaporized? Do you recall from Chapter
18 how energy is related to the mass and the heat of vaporization?
How is resistance related to resistivity? How is the rate of energy
transfer related to the resistance and the current?